Because AD8369 just have 45dB dynamic gain range, but I need 80dB dynamic gain range in circuit. So I want to use 2pcs AD8369 cascading to achieve 80dB dynamic gain range. Following pictrue is my circiut use 2 pcs AD8369 cascading, dose it right?
Yes, this is the right way to connect the AD8369 in cascade. The only point I want to add is that since the input and output have 200 ohm differential impedance, the lines connecting all of these pins should have100-ohm impedance. You did not mention the frequency of operation. If the line length is short compared to quarter wavelength on the PCB (~ 74mm @ 600 Mhz), then just using a narrow trace to minimize capacitance will be adequate. The device is internally DC coupled, and the caps on pins 9 & p10 set the low frequency cut-off corner. Page 14 on the datasheet contains a description about the value selection.
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